We are currently investigating the source of following errors in our systems. Maybe there is something wrong with our setup. We are using stepper motors with third party drivers and incremental encoders. We are using our own test program which performs random movements and then displays the actual position reached, plus the following error, and stops if a certain following error value is exceeded after finishing the motion.
The values read by our program and by the "advanced" data of the 1-axis interactive menu of NI-MAX are identical. However, if we watch the graph of the following error in the "misc plots" section, during the movement it shows values at least similar to those shown in the "advanced" display. When exceptional high following errors are detected by our program after finishing a cycle, our program shows following error values still identical to those in the "advanced" menu. When we switch to the "misc plots" section, however, at the end of the plot the following error is much lower (and well inside our limits).
Where does the plot display get its data from? Does it read the register with the following error data at the same time as the routine displaying this value in the "advanced" menu? The values shown by the plots at the end of a cycle are always OK and now we have some problems which value to believe ...
